Subtracting Four Digit Numbers

Subtracting four digit numbers can be a challenging task. However, if your child has already perfected basic subtraction, this will not be incredibly difficult to master. One thing to keep in mind, is that in this particular lesson, we will not be focusing on how to find negative answers. As a result, the first number needs to always be bigger than the second number. For example, the problem needs to read 3-2, not 2-3. 2-3 would give us a negative answer: -1. In this case, we only want to focus on getting positive answers.

Example:

Please refer to the image above:

The first thing you need to do is read the problem starting from the far right, moving left with each place value. Next, continue with basic subtraction by reading the problem vertically. You will first begin by subtracting 4 and 2, getting the answer: 2.

Next, subtract 5 from 5 and get the answer: 0.

Now here comes the tricky part. Because the 3 in the hundreds place is smaller than the 4 in the same column, you will need to change the 3 to 13. You are able to do this because you are borrowing 10 from the number in the thousands place: 4. This way, you can get a positive single digit number. 13 – 4 = 9.

The number in the thousands place needs to be changed from 4 to 3 since you borrowed 10 to turn the 3 in the hundreds place into a 13. As a result, 3 – 3 = 0.

The final answer to this problem ends up being 902.

The concept is exactly the same when dealing with more than four digit numbers. Use this step-by-step problem as a guide to teach your child how to subtract four digit numbers. After mastering this basic skill, they can subtract with multiple digit numbers.